Problem Eyes

The following drawing shows (a) a normal eye, (b) an eye that is myopic (near-sighted), and (c) and eye that is hyperopic (far-sighted).  The myopic eye is too short and/or the eye has too much power.  The hyperopic eye is too long and/or the eye has too little power.

A person with a myopic eye can see things up-close, but things far away are blurry.  The correction for a myopic eye is to wear a negative lens:

A person with a hyperopic eye can see things far-away, but things up-close are blurry.  The correction for a hyperopic eye is to wear a positive lens: